The electron beam irradiation apparatus irradiates a mask with an electron beam, for example, in a manufacturing process of a semiconductor device and thereby improves etching resistance of the mask. The electron beam irradiation apparatus is provided with a deflector. The deflector deflects the electron beam, so that the electron beam irradiation apparatus can irradiate an arbitrary area of the mask with the electron beam.
However, the deflection sensitivity of the deflector (how much the electron beam is deflected) is not necessarily constant, but may vary, so that the electron beam may not be irradiated to a desired area. Therefore, it is desired to improve the deflection sensitivity of the deflector in the electron beam irradiation apparatus.
According to one embodiment of the present disclosure, provided is a deflection sensitivity calculation method for calculating deflection sensitivity of a deflector in an electron beam irradiation apparatus that irradiates an irradiation object on a stage with an electron beam by causing the deflector to deflect the electron beam, the deflection sensitivity calculation method including:
irradiating an area that covers an adjustment plate with an electron beam by scanning a deflection parameter that controls deflection of the deflector in a predetermined width, a size the adjustment plate being known, the adjustment plate being placed on the stage, the adjustment plate detecting a current corresponding to the irradiated electron beam;
detecting a current value detected from the adjustment plate;
forming an image corresponding to the detected current value, a number of pixels of the image being known;
calculating the number of pixels of a portion corresponding to the adjustment plate in the formed image; and
calculating the deflection sensitivity of the deflector based on the size of the adjustment plate, the predetermined width for scanning the deflection parameter, the number of pixels of the image, and the number of pixels of the portion corresponding to the adjustment plate in the image.
According to one embodiment of the present disclosure, a deflection sensitivity calculation system for calculating deflection sensitivity of a deflector in an electron beam irradiation apparatus that irradiates an irradiation object on a stage with an electron beam by causing the deflector to deflect the electron beam, the deflection sensitivity calculation system including:
an adjustment plate that detects a current corresponding to the irradiated electron beam, a size of the adjustment plate being known, the adjustment plate being placed on the stage;
an ammeter that detects a current detected from the adjustment plate while an area that covers the adjustment plate is irradiated with the electron beam by scanning a deflection parameter that controls deflection of the deflector in a predetermined width;
an image forming module that forms an image corresponding to the detected current value;
a number of pixels calculator that calculates a number of pixels of a portion corresponding to the adjustment plate in the formed image; and
a deflection sensitivity calculator that calculates the deflection sensitivity of the deflector based on a size of the adjustment plate, the predetermined width for scanning the deflection parameter, the number of pixels of the image, and the number of pixels of the portion corresponding to the adjustment plate in the image.